Films are rated by authorized agencies or associations in terms of violence, sexuality, drug abuse, and other criteria. Ratings are used to determine the suitability of films among different age groups. For example, the Motion Picture Association of American (MPAA) is an American agency representing Hollywood studios. The primary MPAA ratings are: G (General audiences), PG (Parental guidance suggested/some material might not be suitable for children), PG-13 (Parents strongly cautioned/some material may be inappropriate for children under the age of 13), R (Restricted/under 17 not admitted without parent or adult guardian), and NC-17 (No one 17 and under admitted). Rating agencies exist in other countries also. It is often difficult to compare ratings between two countries because the ratings often reflect the subjective opinions of the board members of the rating agency. It is further difficult to compare ratings between two countries because the criteria adapted to determine the rating can vary widely between two different film rating systems. For example, violence is less a concern than sexual content in the United States, however, it is the opposite in many European countries. It is also difficult to compare ratings between two countries because the hierarchy of rating classifications also varies from country to country. For example, Belgium has only three classifications for movies, whereas Singapore has seven classifications and Britain has eight classifications.
Existing streaming movie providers allow parents to set parental controls from either the client or the server end. In an example of parental controls at the server end, parents can log on to a streaming on-line account and set the parental control level as PG so that any movie ranked above PG will be blocked from streaming from the server directly. In an example of parental controls at the client end, parents can create a client parental control password and set the parental control level at the client so that any movie ranked above PG will be grayed out by the client even though they are provided by the server. These existing mechanisms of parental control, however, sometime fail due to: 1) a movie with inappropriate content not being appropriately blocked and then being accessed by a young viewer; or 2) a movie without inappropriate content being blocked and not being able to be accessed by a young viewer.